For a long time it was believed that brain cells did not regenerate. Once they died, they were gone.
There is some good new out there now. Research shows that neurogenesis is in fact possible, and the best way to a achieve it is through movement. Movement stimulates the release of something called BDNF. BDNF, which stands for Brain Derived Neurotrophic Factor, is a growth factor that stimulates neurogenesis.
As of recently they have even pinpointed which type of movement stimulates the greatest BDNF response. It turns out that walking briskly is the exercise of choice. While a good HIIT workout has its own benefits, fast paced walking is the one that will make those brain cells grow.
So grab a buddy, a comfy pair of sneakers, and get on the road. I opt to walk at least two times per week, usually catching up with friends or listening to a book on audible.